lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Add 'discard' request handling

Browse Source 
Some block devices benefit from a hint that they can forget the contents
of certain sectors. Add basic support for this to the block core, along
with a 'blkdev_issue_discard()' helper function which issues such
requests.

The caller doesn't get to provide an end_io functio, since
blkdev_issue_discard() will automatically split the request up into
multiple bios if appropriate. Neither does the function wait for
completion -- it's expected that callers won't care about when, or even
_if_, the request completes. It's only a hint to the device anyway. By
definition, the file system doesn't _care_ about these sectors any more.

[With feedback from OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> and
Jens Axboe <jens.axboe@oracle.com]

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
David Woodhouse
2008-08-05 18:01:53 +01:00
committed by Jens Axboe
parent d628eaef31
commit fb2dce862d
6 changed files with 130 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/fs.h
View File

@@ -86,7 +86,8 @@ extern int dir_notify_enable;
#define READ_META (READ | (1 << BIO_RW_META))
#define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNC))
#define SWRITE_SYNC (SWRITE | (1 << BIO_RW_SYNC))
#define WRITE_BARRIER ((1 << BIO_RW) | (1 << BIO_RW_BARRIER))
#define WRITE_BARRIER (WRITE | (1 << BIO_RW_BARRIER))
#define WRITE_DISCARD (WRITE | (1 << BIO_RW_DISCARD))
#define SEL_IN 1
#define SEL_OUT 2